Moto Sakura Castle, Japanese castle ruins in Chiba Prefecture, Japan.

Moto Sakura Castle is a fortress site in Chiba Prefecture that spans the border between Sakura City and Shisui Town. The ruins feature stone walls, earthen ramparts, and multiple gates that reveal the layout of a medieval defensive stronghold.

Built during the Bunmei era (1469–1486), the castle was the base of Chiba Suketane, who took the Chiba headship with backing from the Koga kubō Ashikaga Shigeuji. A record of 1484 notes that Chiba Takanetane moved his castle to Sakura, and by 1490 the castle town was being laid out. It remained the Chiba clan's headquarters for nine generations until the clan was dispossessed after the 1590 Odawara campaign.

The castle's name sets it apart from nearby Sakura Castle, built later: "Moto" marks the earlier stronghold of the Chiba clan, who held it for nine generations. The later castle gave its name to the town of Sakura, while the old site kept the prefix. The castle town itself was moved to Shisui-juku, which became a post station on the Narita road.

Entry to the site is free and open during daylight hours, with an information center on-site to answer questions. The walk from the nearest station is short and follows clear paths through quiet areas.

The castle's earthworks survive almost intact: earthen ramparts and dry moats trace the inner and outer enclosures. In 1998 the site became the first castle in Chiba Prefecture designated a national historic site, and in 2017 it was listed as No. 121 among the Continued 100 Fine Castles of Japan.